This thesis presents experimental analysis of polariton dynamics in semiconductor umicrocavities. A microcavity is a monolithic structure composed of two distribnted Bragg reflectors which are separated by a layer of active material. Strong coupling between excitons residing in the active layer and photons confined within the cavity leads to new eigenstates of the system, called microcavity exciton-polaritons. The dynamics of these qnasi-bosons are stndied using a range of optical spectroscopy techniques. It has been shown previously tlmat resonant injection of polaritons nsing a continuous wave laser allows the rnicrocavity to operate as an optical parametric oscillator. A full study of the recovery dynanucs of a transiently destabilized nucrocavity optical parametric oscillator is made in this thesis. Destabilization was achieved by optically injecting surplus polaritonms into a systeum that had reached equilibrium. The dynamics of the scattering processes is theoretically described using a rate equation model. Bose condensation and polariton lasing have recently been demonstrated at liquid hehum temperatures. In this thesis, we use a hybrid bulk gallium nitride nuicrocavity to demonstrate the operation of the first room temperature polariton laser. Polarisation measurements also show spontamieous symmetry breaking, implying observation of the first room tenmperature Bose-Einstein condensate.